Tests whether two floating-point numbers are approximately equal. : float « Data Types « C++ Tutorial

#include <iostream>
#include <algorithm>
#include <cmath>
using namespace std;

bool approx_equal(double x, double y)
   const double EPSILON = 1E-14;
   if (x == 0) return fabs(y) <= EPSILON;
   if (y == 0) return fabs(x) <= EPSILON;
   return fabs(x - y) / max(fabs(x), fabs(y)) <= EPSILON;

int main()
   double x;
   cout << "Enter a number: ";
   cin >> x;

   double y;
   cout << "Enter another number: ";
   cin >> y;

   if (approx_equal(x, y))
      cout << "The numbers are approximately equal.\n";
      cout << "The numbers are different.\n";

   return 0;

2.9.1.float point constant number
2.9.2.float number array
2.9.3.Read float point numbers from keyboard and save them to a float array
2.9.4.Type Conversion: from float to double
2.9.5.constant floats, floating point variables
2.9.6.Local Float Variables and Parameters: convert the temperature in Fahrenheit to Celsius
2.9.7.Display decimal and float with format
2.9.8.Define function whose parameter and return value are both float
2.9.9.Tests whether two floating-point numbers are approximately equal.
2.9.10.Controlling the printing of trailing zeros and decimal points for floating-point values.
2.9.11.cin handles double and float type values